In a conventional motorcycle, rotation of a crank shaft inside a crankcase cover of an engine is changed by a transmission. In this transmission, a multistage shifting mechanism including a main shaft of a gearbox, a drive shaft, and multistage change gears is housed therein, and a clutch for connecting/disconnecting transmission of rotation when shifting the change gears is provided. Moreover, an automatic transmission control device for automatically actuating the clutch and shifting the change gears of the transmission, in other words, an AMT (automated transmission) mechanism is provided.
This AMT mechanism includes a clutch actuator for actuating the clutch, a shift actuator for shifting the change gears of the transmission, and other components necessary for the AMT. The AMT mechanism is either semi-automatic or full-automatic. This AMT mechanism is provided beside and below the crankcase cover in a car width direction.
Incidentally, in the conventional motorcycle, the AMT mechanism is provided beside and below the crankcase cover in the car width direction, thus there have been problems that the AMT mechanism hits the ground in the first place and suffers damage when banking the motorcycle while cornering, and that a bank angle of the motorcycle is limited while cornering because of the AMT mechanism hitting the ground.
Moreover, there has been a problem that the AMT mechanism is susceptible to damage when the motorcycle tumbles over, and it is highly likely that shift change becomes impossible.